How can I activate my Apple ID?

Contact Apple ID Support for assistance.  See the Apple Support articles below for contact information.  

Apple ID - Official Apple Support.   -

Contact Apple for help with Apple ID account security - Apple Support.  *   (Link doesn’t always load)  

Get Support      -    Work through the screens to get a chat option. You may have to pick a slightly different problem.

Apple Support schedule phone call.   -

If necessary, use Twitter or Messages.

Apple on Twitter     

Messages chat with Apple  

From the Apple Support article below. 

Without proof of your identity via security questions and other carefully selected criteria, Apple Support can't help you reset a password or perform any other actions on your account. These policies are audited and reviewed on a regular basis.

Security and your Apple ID - Apple Support.      *

How did it get de-activated? And in what context?

Hi Eric, this originated in iPhone forum but seems to have been relocated.

Thanks.

You are welcome.